Abstract
Ant coexistence was studied in adjacent areas of upland tropical forest, grassland and agricultural land in San Lorenzo, Puerto Rico. Data on food utilization, daily activity, nesting sites, microhabitat utilization and interspecific aggression were collected. Ant tolerance to 45.degree.C was determined in the laboratory. Agricultural and grassland ants eat grain, liquid food or insects, or grow fungus; only liquid drinking and insectivorous ants occurred in the forest. Some species within food groups in the agricultural and grassland ants differed in size of food consumed or daily activity. Some species from agricultural land were restricted to different crops, but spatial microhabitat utilization contributed little to species separation. Forest species differed in their use of litter depths, daily activity and microhabitat. Results of interspecific aggression were influenced by priority effects and microclimate. Some species probably coexist by nonequilibrium processes or by stochastic events.